Sterilization and Polymers

Tech Tip

Sterilization capabilities are an important consideration for the selection of polymeric adhesives, sealants and potting compounds for use in medical applications. Medical devices can be divided into disposable or reusable categories. In general, demands for sterilization performance are more rigorous for reusable products than for disposable products.

Sterilization Methods for Reusable vs. Disposable Medical Devices

The most widely employed sterilization methods for medical devices include autoclaving, radiation (electron beam or isotopes), ethylene oxide, plasma or corona discharge and liquid sterilants (hydrogen peroxide, glutaraldehyde, etc.). Epoxy polymers are among the most widely employed adhesives, sealants and potting compounds for repeated sterilization such as autoclaving and liquid sterilization. For disposable devices, the more common sterilization techniques are ETO, gamma radiation or liquid sterilization.

Master Bond Sterilization Resistant, Medical Grade Adhesives

Master Bond has developed a wide variety of adhesives, sealants and potting compounds for the assembly of reusable and disposable medical devices, including many Class VI biocompatible materials, which are specially designed to withstand the sterilization requirements for a particular application without sacrificing the performance properties of the material.

EP42HT-2Med is a two part, room temperature curable, USP Class VI certified epoxy that withstands repeated sterilization, including autoclaving and chemical sterilants. It is also castable in thicknesses up to 3 inches and has a service temperature range of -60°F to 450°F. EP41SMed is a rapid setting, low viscosity, USP Class VI, two part epoxy system with superior resistance to cold sterilants, ETO and gamma radiation. It can be used in both reusable and disposable medical devices. UV10Med is a USP Class VI approved, low viscosity, optically clear system that cures rapidly under UV light. It resists liquid sterilants, ETO and gamma radiation and is widely used in disposable devices. EP3HTMed is a one component, no mix, USP Class VI epoxy that resists repeated autoclaving and chemical sterilization. It has an unlimited working life and cures fast at elevated temperatures (minimum 250°F).

Discuss your Application Product Selector

Featured Products in this Tech Tip

EP42HT-2Med

Low viscosity, two part epoxy with outstanding chemical resistance. Passes USP Class VI biocompatibility tests. Capable of withstanding repeated sterilization cycles including radiation, EtO, chemical sterilants, autoclaving. Serviceable from -60°F to +450°F. Cures at room or elevated temperatures. Available in amber-clear and black colors. Castable in thicknesses up to 2-3 inches.

UV10Med

USP Class VI approved, optically clear adhesive. Fast curing. Resists many chemicals and sterilants. Electrically insulative. High bond strength to metals, glass, plastics such as polycarbonates, acrylics. Serviceable from -60°F to +250°F.

EP3HTMed

Rapid curing, one part epoxy. Meets USP Class VI biocompatibility standards. Thixotropic paste viscosity. High shear strength. Superb resistance to autoclaving, chemical sterilants, radition, EtO. Serviceable from -60°F to +400°F.

EP41SMed

Biocompatible. Meets USP Class VI test specification. Impressive resistance to chemical sterilants including ethylene oxide, bleach, glutaraldehyde, hydrogen peroxide based systems and paracetic acid type compounds. High bond strength. Electrical insulator. Fast curing. Quick handling time. Service temperature range -60°F to +250°F.

Discuss your Application Product Selector

Latest Developments

Case Study

EP114: Utilized to produce nanocomposites via vacuum infiltration

Master Bond EP114 is a two-component nano silica filled epoxy system which offers excellent dimensional stability and a very high glass transition temperature (Tg > 200°C upon curing. Its ultra-low initial mixed viscosity (500–1500 cps at room temperature) can be further reduced by preheating to a slightly higher temperature, making EP114 ideal for vacuum infiltration to produce dense nanocomposites, as shown in the case study below.

EP42HT-2ND-2Med Black Two Part Epoxy System

Technical Data Sheet Excerpt

EP42HT-2ND-2Med Black Product Information

Two component epoxy paste adhesive. Resists sterilization exposure. USP Class VI approved. Outstanding thermal stability and electrical insulation properties. Cures at ambient temperatures. Withstands multiple cycles of autoclaving, radiation, EtO and chemical sterilants. Post curing is recommended to optimize physical properties. Serviceable from -60°F to +450°F.

White Paper

Epoxy Compounds Get Even Tougher

With adhesive products, high performance and rigidity are often thought to go hand in hand. And it is true that the very best strength, thermal, chemical and electrical properties tend to be found in rigid compounds, especially epoxies. Yet there is a growing class of adhesives, sealants and coatings that add ductility to the long list of desirable epoxy properties. Master Bond’s white paper examines the use of these toughened epoxies.

White Paper

Spotlight on Silicones

Silicone adhesive systems have several important performance characteristics that distinguish them from other adhesive families. Learn more about their unique combination of flexibility, high temperature resistance, and more specialized engineering properties.

White Paper

Electrically Conductive Adhesives Make Right Connections

As electronic circuits become more complex, engineers are finding new ways to assemble and package them. Electrically conductive adhesives provide durable bonds with conductive paths to suit a variety of electronics applications. They can be engineered to combine bond strength and electrical conductivity with other service-critical properties.

Technical Data Sheet Excerpt

EP37-3FLF Product Information

Highly flexible, low viscosity, optically clear adhesive. Resistant to severe thermal cycling and thermal shock. Bonds well to dissimilar substrates. Low exotherm system. Long working life. Superior electrical insulation properties. Service temperature range from 4K to +250°F. One to one mix ratio by weight or volume.

Lab Report

Testing Adhesives for Resistance to Xylene

Many Master Bond epoxy systems are formulated with superior chemical resistance. In the lab, we continually test our materials by exposing them to specific chemicals over a long period of time. A common way of testing the chemical compatibility of an epoxy is immersing a sample in a chemical and measuring its change in weight over time. A significant loss or gain in weight would indicate a decreased ability of a material to stand up to chemical exposure. These tests allow us to more accurately recommend the right adhesive based on specific application requirements.In this experiment, we focused on testing our epoxies for their resistance to xylene. The compounds Master Bond used for testing are a variety of two component epoxies and one component UV curing systems with good overall chemical resistance. For the first round of testing the products tested were EP41S-5LV, EP42HT-2AO-1, EP46HT-2AO Black, UV16, UV22DC80-1, and UV26. For the second round of testing the products tested were EP125, EP42HT-2 and UV25. For the final round the products tested were EP41S-5, EP41S-1HT, EP62-1HT and EP62-1. These were compared against the resistance of a generic or standard non-chemically resistant epoxy. A few thin castings, roughly 2 inches in diameter and around 0.125 inches thick, were made for each product and cured in accordance to their specifications. Once the cured samples were created and initial weight was recorded, we submerged them in xylene. Then we continued recording weekly weight measurements. We carried on these tests with frequent weight recording for varying lengths of time based on the products performance. Below you will see the results for soaking results for around 10 months in the first batch, 2 years for the next batch, and greater than 2.5 years for the third batch of products. The castings were weighed periodically and the graphs shown below demonstrate the percentage of weight change over time.For the purpose of comparison, please notice that for each testing timeframe, a casting of a standard epoxy was also tested under these same conditions which served as a reference. As can be seen in the graphs, the standard epoxy was not as resistant to xylene as the other epoxies tested. It demonstrated a significantly greater change in weight over time, and the casting ultimately dissolved in xylene after 15 weeks.In general, a swelling of less than 4-5% can be considered excellent, especially since this test may be more rigorous compared to actual service conditions. It is also worth noting that in the context of a bonded joint or a potted assembly the exposure to xylene might not be as severe or direct as in the above test conditions.Please note, when choosing an epoxy for an application where the resistance to xylene is critical, many other factors must be considered in addition to the chemical resistance. Each of the epoxies in the charts above offers a distinct set of performance properties. For example, if thermal conductivity and high temperature resistance are needed, EP46HT-2AO Black may be a good option. If a fast cure is required and there is full access to a light source with no shadows, UV26 can be considered. For longer term exposure to xylene over several months to a year or longer, the likes of UV25, EP125 EP41S-5, and EP62-1 are excellent candidates. They all need to be processed or cured differently and although some of them can be cured at room temperature alone, for enhancing/optimizing chemical resistance especially to xylene, it is critical to add heat.Disclaimer: The findings in this article are not meant to be used for specification purposes.

Want to Stay Updated?

Subscribe to Our eNewsletter

Get the latest news, insightful content, and helpful tips delivered weekly to your inbox.